Hierarchically Porous Polymeric Carbon Nitride as a Volume Photocatalyst for Efficient H2 Generation under Strong Irradiation

Generally, photocatalytic reaction efficiency decreases quickly with increasing irradiation intensity. Thus, it is a great challenge to achieve a high reaction efficiency under strong irradiation. Volume photocatalysis (VPs) is a new strategy for improving photocatalytic reaction efficiency. Herein, hierarchically porous polymeric carbon nitride (PCN) U-PCN-480 as a novel volume photocatalyst is fabricated by a template-free pyrolysis of needle-like urea. It is found for the first time that the hierarchical pore structure endows U-PCN-480 with the enhanced photoabsorption ability under strong irradiation. Consequently, Pt/U-PCN-480 displays excellent VPs activity for hydrogen evolution in the formic acid reaction system. Notably, the activity and apparent quantum efficiency (AQE) are significantly enhanced with increasing irradiation intensity, and the AQE reaches 62.7% and 70.4% at 400 and 380 nm with the irradiation intensity of 30.5 mW cm(-2), respectively, the highest values among the reported data for PCN-based photocatalysts. This effect of enhanced activity and AQE is the result of the synergy between VPs and the enhanced photoabsorption. The findings offer an approach to resolve the difficult problem of low photocatalytic reaction efficiency under strong irradiation and open a way to develop efficient photocatalyst materials and reaction systems.

Automated summary

The study demonstrated the fabrication of hierarchically porous polymeric carbon nitride (PCN) U-PCN-480 by template-free pyrolysis of urea, showing enhanced photoabsorption ability and excellent volume photocatalysis (VPs) activity under strong irradiation for hydrogen evolution. The synergy between VPs and enhanced photoabsorption was found to be crucial for the significantly enhanced activity and apparent quantum efficiency (AQE). These findings provide a new approach to developing efficient photocatalyst materials and reaction systems under strong irradiation.